Nuclei

Q1.

The energy liberated on complete fission of 1 kg of $U 92235$ is (Assume 200 MeV energy is liberated on fission of 1 nucleus)

(1) $8.2 \times 10^{10} J$

(2) $8.2 \times 10^{9} J$

(3) $8.2 \times 10^{13} J$

(4) $8.2 \times 10^{16} J$

Explanation:

(3) Mass of a uranium nucleus $= 92 \times 1.6725 \times 10^{- 27} + 143 \times 1.6747 \times 10^{- 27} = 393.35 \times 10^{- 27} kg$

Number of nuclei in the given mass $= \frac{1}{393.35 \times 10^{- 27}} = 2.542 \times 10^{24}$

Energy released $= 200 \times 2.542 \times 10^{24} MeV$

$= 5.08 \times 10^{26} MeV = 8.135 \times 10^{13} J = 8.2 \times 10^{13} J$

Q2.

A certain mass of hydrogen is changed to helium by the process of fusion. The mass defect in the fusion reaction is 0.02866 u. The energy liberated per nucleon is: (given 1 u = 931 MeV)

67 MeV
26.7 MeV
6.675 MeV
13.35 MeV